Chem Flashcards
what is an atom?
the most basic complete unit of an element
Element
Pure Substances that cannot be broken into simpler substances
What are the three fundamental particles/ subatomic particles of an atom?
proton, neutrons, and electrons
Valence Electrons
the electrons in the outer most shells that can bond
The elements in the first period have how many shells
1 shell - s
Period or row 2 has subsell s and subshell p
The elements in the 7th period have how many sub shells
7
Atomic number
number of protons in the nucleus of an atom
atomic mass
the sum of the masses of protons and neutrons in one atom of an element
what are electrons and where are they located?
Electrons are negatively charged subatomic particles that move around the center of the atom in regions known as orbitals
how many electrons can each orbital hold
2 electons
Orbitals group together to make up a …
shell
What are the subshells labeled as
S,P,D, F with s being closest to the nucleus
What is the most stable configuration for valence electrons
atoms in their most stable state when their valence shells are filled.
What are the two exceptions to the 8 valence electron rule
hydrogen and helium
What two subatomic particles are in the nucleus
neutrons and protons
Atomic mass units
amu
why are electrons not included in the atomic mass
they have such a slight mass that they are not inlcuded
how does atomic number ( protons) change across the periodic table
the atomic number increases left to right and
Maximum Number of Electrons for an S orbital
2
Maximum Number of Electrons for an P orbital
p = 6
Maximum Number of Electrons for an d orbital
d = 10
Maximum Number of Electrons for an f orbital
f = 14
Orbitals in period 1, 2, 3, 4
1 = s
2 - s,p
3 = s, p,d
4 -= s, p,d, f
HOW ARE COLUMNS Arranged
each column ( group) contains elements that have similar chemical and physical properties
Isotopes
Atoms of the same element that have different numbers of neutrons but the same number of protons and electrons.
Ion
a positively or negatively charged atom or molecule
cation
positively charged ion
anion
negatively charged ion
typically metals that are on the left side of the periodic table become what type of ion
lose electrons when they form ions
elements in the upper right of the periodic table, the nonmetals become what type of ion
gain electrons to form anions
Reactions of metals and nonmetals form compounds with what type of bonds
ionic bonds
ionic bonds
the bond between two oppositely charged ions
the ionic bond occurs when the metal transfer electrons to the nonmetal
reactions between nonmetals result in what type of bond
covalent bond - sharing of electrons
Physical Properties of Substances
observable characteristics that change without modifying the identity of the substance.
ex. state of matter
Three common states of matter
solid, liquid, gas
Intensive Properties
physical properties that are independent on the amount of substance present
ex: density, color, conductivity
extensive properites
Physical properties that are Dependent on the amount of substance present
ex: length, volume, mass
Mass
a measurement of inertia, commonly considered the amount of material contained by an object and causing it to have weight in a gravitational field
Volume
the amount of space something takes up
Length
Measurement of distance from end to end
Can volume and mass independently be used to identify and substance
No, density ( mass/ volume) is an intensive property that is constant for each substance and can be used for identification
density
Mass/ Volume - an intensive property
denser substances will sink below less dense substances
Molecules above absolute are
in constant motion
0 Kelvin = X Celcius
-273 celcius
Molecule
an arrangement of two or more atoms bonded together
How does heat change an atoms motions
the amount of movement within a molecule ( and atom) increases in response to thermal energy ( heat)
Intermolecular forces
molecule to molecule bonding
What is the fourth phase of matter
plasma
plasma
clear pale yellow components of blood that caries red blood cells, white bc, and platelets throughout the body.
what are molecules in constant motion?
bc their atoms are in constant motion - making and breaking bonds
temperature
a measure of the average energy of the molecules within a substance - aka the hotness or coldness of a substance
are heat and temperature the same?
no
heat
a measured unit of calories or joules
heat can be thought of as energy that is generated by or applied to a substance or system
The amount of energy needed to change the temperature of one gram of a molecule by 1 degrees C is called what
its specific heat of capacity
The phase of a substance depends on two conditons:
temperature and pressure
how does increasing temp and increasing pressure affect movement of particles
increasing temp as the tendency to move particles apart
increasing pressure has a tendency to move particles of matter together
Liquid state
definite volume but not definite shape
lower temperature of a substance correlates to
less IMF movement
Evaporation
liquid to gas
gas
a state of matter composed of molecules in constant random motion
no definite volume or shape - it is highly compressible
condensation
gas to liquid
triple point
the temperature and pressure at which solid, liquid, and gas phases of a pure substance coexist
deposition
the transition of substance from gas to solid
sublimation
the transition of a substance from solid to gas
critical point
the temperature above which a substance coexists in both its liquid and gas states
Chemical Reaction
a process in which one bonding arrangement among atoms is exchanged for a different bonding arrangement
Molecule
any arrangement of two or more atoms bonded together
Valence electrons
The electrons in the outermost shell of an atom have the highest energy and are easily transferred or shared with other atoms
Elements in the same group (vertical column) on the periodic table have
the same number of valence electrons in the same type of subshell ( s,p,d,f)
ionization trend
generally speaking, the left side of the periodic table has elements with low ionization energies - moving to the upper right have high ionization energies and electronegativities so they tend to gain electrons in chemical reactions
ionic bond
the bond between two oppositely charged ions
covalent bond
the result of two or more atoms sharing electrons so both atoms involved becomes more stable
typically, an atom having fewer than four valence shell electrons
will lose its electrons to an atom with more than four valence shell electrons
Solution
a homogeneous mixture of two or more substances whose components are uniformly distributed on a microscopic scale
compound
a substance made of two or more elements
reactants
in chemical equation, the substances on the left side of the equation; the starting materials in a chemical reaction
products
the substances that are formed in a chemical reaction
metal
a substance that is a good conductor of electricity and heat, forms cations by loss of electrons, and yields basic oxides and hydroxides
a mole
a unit - 1 mol = 6.022 * 10^23 particles
activation energy
the minimum energy required to initiate a chemical rxn
pH
the measure of acidity or alkalinity
Catalyst
a substance that increases the rate of a chemical reaction without undergoing
endothermic rxn
involving absorption of heat
exothermic rxn
involving the release of heat
Increasing the concentration of reactants
increases the probability that reactants will come in contact with each other
if products are withdrawn from the reaction as they form
the rate of production formation increases
increase in pressure will
increase the number of interactions between reactant molecules and thus, increase the rate of reaction
activation energy
the minimum energy required to initiate a chemical reaction
the smaller the activation barrier the
faster the rate of the reaction
the most important biological catalysts are
enzymes
once equilibrium is reached
the rates of the forward and reverse reactions are equal. there is no change in the concentration of reactants or products
what causes change of direction of a reaction?
change in concentration can
decreasing the concentration shifts the reaction to the left and increasing the concentration of a reactant shift the reaction right.
think lungs at co2 - decreasing the concentration by exhaling drives the reaction to form more of it
Le Chatelier’s principle
when a chemical reaction at equilibrium is perturbed, it responds by going in the direction that restores the equilibrium
changing [pressure and temperature can also perturb a reaction that is at equilibirum
If the reaction is exothermic, raising the temperature would
shift the reaction to the left
Increasing the temperature of an endothermic reaction will
increase the rate of reaction
CO2 is _________ in respiring tissue, but _________ in the lungs
Co2 is formed in respiring tissue and expelled via exhalation in the lungs; therefore, CO2 concentration is high in respiring tissue and low in the lungs - high Co2 favors the forward direction, and low Co2 favors the reverse
Solutions
are homogenous mixtures of two or more substances whose components are uniformly distributed on a microscopic scale
Polar Bonds
is a covalent bond in which the atoms have an unequal attraction for electrons, and so the sharing is unequal.
Nonpolar covalent Bonds
is a covalent bond in which the bonding electrons are shared equally between the two atoms. In a nonpolar covalent bond, the distribution of electrical charge is balanced between two atoms
Hydrogen Bonding
a weak bond formed between the partial negative region and partial positive region
( ex. neg of oxy and pos of hydrogen in water)
Water is the universal
solvent
Adhesion
the tendency of dissimilar particles or surfaces to cling to one another
Cohesion
stick to itself
cohesion creates
surface tension
and with adhesion it helps creates capillary action that moves water up the plant xylem
water has a ( high/low) specific heat capacity
high specific heat capacity
why is water denser as liquid than solid
due to hydrogen bonds liquid water is more dense than solid water.
ice floats on water because more hydrogen bonds form between water with lower Kinetic energy
in other words - for the same mass of water, solid water takes up more volume and therefore it is less dense than liquid water
solution
when one substance dissolves into another where the solvent is the substance that dissolves a solute
what is in larger proportion the solvent or the solute
the solvent constitutes a greater proportion of the solution than the solute so the solution exists as the same phase as the solvent
if solute = solid, solvent = liquid … the solution = liquid
hydrophilic
water-loving
hydrophobic
water fearing
solubility of most substances depends strongly on
the temperature, and in the case of gases, the pressure.
the solubility of most solids and liquids _______ as temp increases
increases
the solubility of gas ________ as temp increases
Decreases
saturated solution
a solution containing the maximum possible amount of solute
supersaturated solutions
contain more dissolved solutes than saturated solutions bc the solute is dissolved in the solvent at higher temperatures
Molarity
moles of solute / liter of solution ( mol/L)
Mole fraction
Moles of solute/ total moles present ( mol/mol)
Molality
Moles of solute / kg of solvent ( mol/kg)
Mass percentage
( mass of solute (g)/ mass of solution (g)) * 100
parts per thousand (ppt)
= g solute / kg solution
parts per million (ppm)
mg solute / kg solution
units of ppm or ppb are used to express very low concentrations
parts per billion (ppb)
ug solute / kg solution
units of ppm or ppb are used to express very low concentrations
Ionic bond
transfer due to the attraction of oppositely charged ions that resulted from the electron transfer
dissolution of ionic bonds result in ..
solvent molecules surrounding ions ( rather than uncharged particles)
example - diffusion
ions are unable to pass through the lipid bilayer of a cell membrane so there movement depends on
specialized ion channels on the membrane of cells which use active transport
active transport in cells
movement across a cell membrane that travels against the concentration gradient and thus requires energy
osmosis
the diffusion of water across a semipermeable membrane such as a cell membrane
( water like ions does not move easily though the cell membrane’s lipid bilayer. it moves though pores ( made of aquaporin protein) by way of osmosis which does not require energy use
